1. Field of the Invention
The invention relates to a device for measuring the axial speed of a moving medium or body, in particular of a gas, the device being of the type comprising a light source associated with collimating optics for emitting a beam of parallel rays towards an observed volume, and at least one photodetector associated with focusing optics for receiving backscattered light flux and delivering a signal corresponding to the intensity of the received light flux.
2. Description of the Related Art
Devices of this type have already been used for determining the concentration of a gas present in an observed volume, on the basis of the way the gas absorbs the light flux at certain wavelengths characteristic of the gas.
Proposals have also been made for "lidar" type systems for measuring meteorological parameters such as cloud altitude, wind speed and direction, temperatures at various different altitudes, etc. To do this, it is necessary to make use either of a plurality of laser generators, or a plurality of receivers, or else to change the wavelengths at which the laser generators emit light and/or the wavelengths to which the receivers are tuned, and that is often lengthy and difficult in practice.